Format

Send to

Choose Destination
See comment in PubMed Commons below
J Biol Chem. 1996 Jan 19;271(3):1748-55.

Extracellular domains of the bradykinin B2 receptor involved in ligand binding and agonist sensing defined by anti-peptide antibodies.

Author information

  • 1Institute of Physiological Chemistry and Pathobiochemistry, Johannes Gutenberg University at Mainz, Germany.

Abstract

Many of the physiological functions of bradykinin are mediated via the B2 receptor. Little is known about binding sites for bradykinin on the receptor. Therefore, antisera against peptides derived from the putative extracellular domains of the B2 receptor were raised. The antibodies strongly reacted with their corresponding antigens and cross-reacted both with the denatured and the native B2 receptor. Affinity-purified antibodies to the various extracellular domains were used to probe the contact sites between the receptor and its agonist, bradykinin or its antagonist HOE140. Antibodies to extracellular domain 3 (second loop) efficiently interfered, in a concentration-dependent manner, with agonist and antagonist binding and vice versa. Antibodies to extracellular domain 4 (third loop) blocked binding of the agonist but not of the antagonist, whereas antibodies to extracellular domains 1 and 2 or to intracellular domains failed to block ligand binding. Antibodies to ectodomain 3 competed with agonistic anti-idiotypic antibodies for B2 receptor binding. Further, affinity-purified antibodies to the amino-terminal portion of extracellular domain 3 transiently increased intracellular free Ca2+ concentration and thus are agonists. The Ca2+ signal was specifically blocked by the B2 antagonist HOE140. By contrast, antibodies to the carboxyl-terminal segment of extracellular domain 4 failed to trigger Ca2+ release. The specific effects of antibodies to the amino-terminal portion of extracellular domain 3 suggest that this portion of the B2 receptor may be involved in ligand binding and in agonist function.

PMID:
8576178
[PubMed - indexed for MEDLINE]
Free full text
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk